transonic

9.6

Happens at speeds close to the speed of sound, just below or above it

adjective
/trænˈsɒnɪk/

Specialized

: transónico

As an aircraft passes through the speed of sound at transonic speeds, shock waves form and drag increases.
Transonic Facility

Examples

As an aircraft approaches Mach 1, it experiences transonic speeds where shock waves begin to form.
Sharpened leading edges, called wing-body strakes, also alleviated buffeting on aircraft that were maneuvering at transonic speeds.

Academic text (2003)
And so you're going through this entire aerodynamic regime down to through hypersonic, supersonic, transonic, subsonic.
Sharpened wing designs can help reduce drag when flying at transonic speeds near the sound barrier.
During transonic flight, small changes in speed can lead to significant aerodynamic effects and increased drag.

How Fast

hypersonic

Specialized

4 7.8

supersonic

12 6.7

transonic

Specialized

9.6

subsonic

Specialized

4 6.4

Surface Forms

transonic positive

Morphology

transonic = sonic (semi-transparent) = trans + sonic

Formed by productive prefix 'trans-' + 'sonic'; the technical sense 'speeds close to the speed of sound' is predictable from the parts but is specialized domain knowledge.

Etymology

Transonic combines trans- 'across' and sonic 'sound', so it literally means moving across or near the speed of sound. That's why transonic describes speeds just below and just above the speed of sound.